Radio receiving system



L. COHEN.

RADIO RECEIVING'SYSTEM.

APPLICATION FILED DEC. 28. 191.8-

1,406,442, Patented Feb. 14, 1922..

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- l7 25: I 29H =5 31" H UNITED m-Es PATENT OFFICE.

LOUIS COHEN, OF WASHINGTON, DISTRICT OF COLUMBIA.

RADIO RECEIVING SYSTEM.

Application filed December 28, 1918 Serial No. 268,720.

To all whom it may concern:

Be it known that I, LOUIS COHEN, a citizen of the United States, residing at Washington, in the District of Columbia, have invented a new and useful Improvement in a.

Radio Receiving System, of which the folmagnetic, the latter being a comparatively tight coupling and fixed, thereby to secure high selectivity. All these objects and others will become more apparent upon consideration of a few examples of my invention, and I now proceed to disclose a limited number of specific embodiments thereof. These are shown in the accompanying drawings and the following description refers specifically thereto. It Will be understood that various modifications may be made within the scope of my invention.

In the drawings, Figure 1 is a diagram of an embodiment of my invention involving an audion detector; and Figure 2 is a diagram showing such audion detector and circuit connections for receiving by the beat method.

Referring particularly to Figure 1, the antenna 11 is connected through the adjustable condenser 12 and adjustable coil 13 to ground 15. Atthe ends of the coil 13, one

of which is adjustable at 14, taps are taken to the respective condensers 16 and 17, each of small capacity relatively to the condenser 12. These small condensers 16 and 17 constitute an electrostatic coupling. The opposite terminals of these condensers 16 and 17 are connected to the adjustable condenser 18 and adjustable coil 19 arranged in multiple to constitute a loop circuit. The adjustment of the coil 19 may be effected by shifting the terminal 20. The circuit of the condenser 18 and coil 19 constitute a tuned fsecondary circuit.

the audion 35, the other terminal 26 of the coil 21 going to the 'hot filament 24 fed by the battery 25. The plate 27 is connected through the battery 28, the condenser 29 and head telephone 30 in multiple, and the conductor 31, to the filament 24. 1

,By means of the adjustable condenser 12 and the adjustment 14 on the coil 13, the antenna can be. tuned-to the frequency of the Waves desired to be received. Also by means of the adjustable condenser 18 and the coil 19 adjustable at 20, the loop circuit 18-19 can be tuned to the samelfrequ'ency. Through the tightly coupled transformer 1921 the oscillations of this frequency are communicated with a high degree of selectivity to the audion 35.

Patented Feb. 14, 1922.

the small condensers 16 and 17 is very effective to render the system highly selective with respectto persistent oscillations. That is, i makes the system highly selective to any particular sustained frequency. This idea is involved in my Patent No. 1123098 granted December 29,1914. With respect to disturbances of an impulsive nature, such as highly damped waves or static eflects, the electrostatic coupling 16 and 17 in itself may not exclude such impulsive disturbances, and the addition of the electromagnetic coupling 1921 gives the advantage that it renders the system immune with respect to all electrical disturbances whether persistent oscillations of undesired frequency or of impul sive type. It is an advantage of practical operation that the coupling 19-21 can be fixed for a considerable range of wave lengths so that no adjustment thereof is required.

For the reception of undamped waves by the beat method, I arrange the apparatus as shown in Figure 2, which is substantially the same as Figure 1, except that the conductor 31 is interrupted and its two parts 31 and 31" include between them the coil 32 which is placed in inductive relation with the coil 19. Thus the circuit 18+19 not only has the oscillations of received wave frequency impressed from the antenna, but also oscillates with a slightly different frequency determined by its own constants. These ourrents of two slightly differing frequencies combine and produce a beat effect, this effect being transmitted through the coupling 1921 to the audion.

. last mentioned lead, a loop circuit receiving energy through an electro-static coupling, a coil tightly coupled magnetically to the in- 10 ductance coil of said 100p circuit, and an audion detector connected across said magnetically coupled coil.

LOUIS COHEN. 

